Chapter 16: Respiratory System Infections

Most common microbial portal of entry

Respiratory route

Function of mucus in the upper respiratory system

Warms and humidifies inhaled air and traps microbes and debris.

Function of cilia

Tiny hairs lining the airway that sweep the debris-filled mucus towards the nose and mouth.

Sinusitis

Inflammation of the sinus membranes.

Pharyngitis

When the pharynx (throat) becomes inflamed due to bacteria, viruses, and allergens.

Epiglottitis

Inflammation and swelling of the epiglottis that ca cause a blockage in the airway.

Laryngitis, tracheitis, bronchitis

Laryngitis: inflammation of larynx and leads to temporary once loss due to swelling of vocal cords.

Tracheitis: inflammation of the trachea

Bronchitis: inflammation of the bronchi/bronchioles

Medical term for croup? What is inflamed?

Laryngotracheobronchitis

Combined inflammation of the larynx, trachea, bronchi, and bronchioles

Stridor? Condition associated with Stridor?

Wheezing or loud breathing associated with breathing obstruction.

Croup is characterized by Stridor.

Pneumonia? Function of alveoli?

Term that refers to inflammation of the lungs, especially of the alveoli.

Alveoli work in the transfer of O2 and CO2

Systemic infection

Infections that affect the whole body

Dyspnea

Shortness of breath

Type of microbe that causes the most common respiratory infection (common cold)

Virus

Serovar

Genetically distinct variants of the same species that are distinguished according to their different surface antigens.

What 2 viruses and their serovars are est. to cause 60-80% of all colds

rhinovirus and coronavirus

Why will the vaccine to the common cold never be developed

There are so many viruses that cause colds

Leading cause of the acute lower respiratory tract infections in children under 5 worldwide

Respiratory Syncytial Virus (RSV)

Three more serious illnesses that HPIV infections can cause in children and the elderly.

Human parainfluenza virus infections

1. Croup

2. Bronchitis

3. Pneumonia

3 non-respiratory illnesses that certain Adenoviruses cause

1. Conjunctivitis (pink eye)

2. Gastroenteritis (diarrhea)

3. Bladder infections (cystitis)

What are two important glycoprotein virulence factors located on the surface of the influenza virus?

HA: hemagglutinin

NA: neuraminidase

The Spanish influenza outbreak of 1918 killed millions of people worldwide. What was the reason there was so much death?

The younger adult population had a strong immune responses which led to them experiencing a cytokine storm.

This is an aggressive and out of control immune response that tended to do more harm than good.

Why should you get the flu vaccine every year

The viral candidates usually change from year to year.

Antigenic drift

minor changes through random mutations

Antigenic shift

Undergo a major genetic change, causing major alterations.

Why can individuals who were vaccinated for the flu still contract the flu?

1. A widely circulating strain not included in the vaccine can reduce its efficacy

2. People are already infected with the virus when vaccinated

3. They may be exposed to the strain before their vaccine and their system has already developed immunity.

Severe acute respiratory syndrome 1 and 2 (SARS-CoV-1 and SARS-CoV-2) and middle eastern respiratory syndrome (MERS-CoV) are caused by which type of virus?

Coronavirus

What host cell receptor does the SARS-CoV-2 spike protein bind to?

ACE2

Angiotensin-converting enzyme 2

List five tissues that express ACE2.

1. Kidneys

2. Heart

3. Blood vessels

4. Neurons

5. Lungs

Acute respiratory distress syndrome (ARDS) can be observed in severe cases of COVID-19. What occurs in the body if a patient develops ARDS?

X-rays show shadowy inflamed areas in both the lungs that leads to a sudden a marked reduction in blood oxygenation.

What is the difference between a viral variant and a viral strain?

Variant: an isolate of a virus that has at least one mutation that makes it genetically distinct from the original form of the virus

Strain: when a variant has mutations with physiological consequences (altering viral functions)

What is hanta pulmonary syndrome (HPS) and how is it contracted?

HPS= an acute and potentially fatal respiratory illness that humans can acquire upon inhaling airborne dust particles that contain Hantavirus.

Contracted from rodent urine and feces particles.

Pulmonary edema

Accumulation of fluid in the lungs.

Define otitis media. Why are children especially susceptible to otitis media?

A middle ear infection. Children are susceptible to this infection due to their Eustachian tubes are shorter, narrower, and oriented such that draining into the pharynx is less efficient.

What bacterium is the primary cause of strep throat?

Group A streptococcus (GAS) S. Pyogenes

Besides culturing the pathogen, what test is used to confirm the diagnosis of streptococcal pharyngitis?

A rapid strep test for bacterial antigens

What important virulence factor is produced by Streptococcus pyogenes which helps it invade host tissues?

M protein of S. Pyogenes

What is the etiological agent of scarlet fever?

Erythrogenic toxin-producing strains

Strawberry tongue” and sandpaper rash are clinical signs of which condition?

Scarlet fever

Which S. pyogenes virulence factor causes autoimmune complications to the heart? What is this autoimmune complication of the heart called?

M proteins and cross-reactive antibodies cause autoimmune complication to the heart.

Complication called rheumatic carditis.

Which bacterium causes diphtheria? What is a bull neck that is observed in acute diphtheria infections?

Gram positive rod Corynebacterium diphtheriae.

The neck region swells

If a patient is left untreated after exposure to diphtheria A-B exotoxin, a thickened, leathery structure can form on the throat. What is it called?

Pseudomembrane

What three infections does the DTaP vaccine protect against?

1. Diphtheria

2. Tetanus

3. Acellular pertussis

What is the etiological agent of pertussis? What is the common name for this infection?

Gram-negative bacterium Bordetella pertussis

Define paroxysms. What infection is associated with paroxysms?

Severe coughing attacks

Pertussis infections are associated

Why is it important to get the Tdap booster?

Immunity from the childhood DTaP vaccine is not long lived

What disease was historically known as consumption?

TB

In current times, what is the main pathogen that causes tuberculosis (TB)?

Gram positive Mycobacterium tuberculosis (tubercle bacillus)

What is a granuloma?

Small clusters of immune cells that are filled with infected macrophages to limit spread of TB

During which stage of a TB infection do granulomas form?

Latent TB

How does latent TB progress to an active TB infection?

When the center of the granuloma liquifies and the walls break down. This leads to an active infection that transmits bacterium.

Are US citizens typically vaccinated against TB? What is the name of the tuberculin skin test regularly used to screen health workers in the US?

People in the US are not typically vaccinated against TB.

They go through the Mantoux tuberculin skin test.

48-72 hours after a tuberculin skin test is administered, the injection site is checked for induration. What is induration?

Development of the hardened area at the injection site.

According to the CDC, what disease caused by an infective agent is among the leading causes of death in the US?

Pneumonia

What is ventilator-associated pneumonia (VAP)?

Form of pneumonia that occurs more than 48 hours after a hospitalized parity is put onto a mechanical ventilator.

What is consolidation? What does it look like on a chest x-ray?

The apparent merging of the alveoli when fluid accumulates in the lungs.

Evident as white opaque areas by X-ray imaging

What is a productive cough?

Cough with sputum

What is the most common form of bacterial pneumonia? What bacterium causes it?

Pneumococcal pneumonia

Caused by Streptococcus pneumoniae

What is the commercial name of two vaccines that protect against pneumococcal pneumonia.

Prevnar 13

Pneumovax

What is the etiological agent of Hib pneumonia?

Haemophilus influenzae

True or False? Haemophilus influenzae is the etiological agent of influenza.

False. It is the agent of Hib pneumonia

There are six main bacterial pathogens that cause atypical pneumonia, in which three are zoonotic.

Name the three pathogens that are zoonotic and state the name of the illness each cause.

Q fever- caused by Coxielle burnetti

Psittacosis- Chlaymydophila psittaci

Tularemia- caused by Francisella tularensis

What pathogen causes the most common atypical, community acquired pneumonia?

Mycoplasma Pneumonia

Which genus of bacteria that causes atypical pneumonia was incorrectly categorized as a virus due to possessing virus-like characteristics?

Mycoplasma

What is the etiological agent of Chlamydophila pneumonia?

Chlamydophila pneumoniae

What pathogen causes Legionnaire’s disease and Pontiac fever?

Legionella pneumophila

What is the etiological agent of an atypical pneumonia called psittacosis (also called ornithosis)?

Birds in which animal family are especially likely to be carriers?

C. Psittaci

Birds in the parrot family

What is the etiological agent of an atypical pneumonia called Q-fever? How does someone contract this illness?

Coxielle burnetti

Inhalation of dust or aerosols from feces, urine, or birth products and consuming unpasteurized milk products.

What is the etiological agent of an atypical pneumonia called tularemia? Why is this pathogen considered a potential bioweapon?

Francisella tularenisis

Considered to be one of the most infectious pathogenic bacterium known to cause diseases in humans.

Define mycosis.

Fungal infections

What is the etiological agent of blastomycosis in the USA? What is its common name

Blastomyces dermatitidis

Chicago disease

What does it mean if a fungus is dimorphic?

It is able to exist in two distinct forms.

Define saprophyte

A mold form that thrives on decomposing plant matter in moist soil.

What are the two etiological agents of coccidioidomycosis? Which fungal species causes Valley fever?

Coccidioides posadasii and Coccidioides immitis

C. Immitis causes Valley fever

What is the etiological agent of histoplasmosis?

Histoplasma capsulatum

Opportunistic fungal pathogens cause most ubiquitous mycoses. What group of individuals is most likely to contract these pathogens?

An immuno-compromised host

What is the main fungal genus/species isolated from patients with invasive aspergillosis?

A. Fumigatus

Which fungus causes most mucormycosis infections?

Rhizopus arrhizus

What is the etiological agent of pneumocystis pneumonia (PCP)? Pneumocystis pneumonia is very rare. What people are most likely to contract pneumocystis pneumonia

Pneumocystis jirovecii

most healthy children have been exposed to it by age 4